1. Field of the Invention
The present invention relates to a frame structure, and more particularly to a frame structure for a saddle-type vehicle having a monocoque structure wherein an air cleaner is contained in a main frame.
2. Description of Background Art
Some conventional saddle-type vehicles have a main frame with a monocoque structure that contains an air cleaner in a hollow interior thereof. The main frame of the monocoque structure is arranged such that air which has passed through the main frame and has been purified by the air cleaner is supplied to an engine mounted in a lower portion of the main frame through an intake passageway connected to the main frame. See, for example, Japanese Utility Model Registration No. 2512878.
The structure disclosed in Japanese Utility Model Registration No. 2512878 employs fastener members such as bolts for fixing the filter element of the air cleaner. Since the structure that employs bolts requires a tool for installing and removing the filter element, a working space is required for inserting the tool. In addition, the air cleaner needs periodic maintenance. Thus, a certain working time is necessary to fasten and unfasten the filter element with fastener members such as bolts.